A Two-Channel Silicon Nitride Multimode Interference Coupler with Low Back Reflection

Jonathan Menahem, Dror Malka

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Optical communication systems based on silicon (Si) multimode interference (MMI) wavelength-division multiplexing (WDM) technology can suffer from back reflection. This undesirable characteristic causes losses and is a key problem that can lead to performance limitations. To overcome this limitation, we proposed a new study on how to divide two wavelengths by understanding the light coupling mechanism of the silicon nitride (SiN) MMI coupler over the C-band window and showed four different options to design a two-channel demultiplexer. The best option for a two-channel SiN MMI coupler with low back reflection losses operating in the C-band spectrum was selected. Based on simulation results, the proposed device can transmit two channels with a spacing of 20 nm between wavelengths in the C-band. Moreover, the device has a low power loss range of 0.895–0.936 dB, large bandwidth of 16.96–18.77 nm, and good crosstalk of 23.5–25.86 dB. Usually, a unique design such as angled MMI is required when using Si MMI technology to reduce the back reflection losses. Due to the use of SiN, which has a low refractive index, we obtained a 40.4 dB back-reflection loss without using this angled MMI design. Therefore, this MMI demultiplexer based on SiN can be used in optical communication systems based on the WDM technique to obtain a high data transfer rate in conjunction with low back-reflection losses.

Original languageEnglish
Article number11812
JournalApplied Sciences (Switzerland)
Issue number22
StatePublished - Nov 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 by the authors.


  • BPM
  • FDTD
  • MMI
  • PIC
  • SiN
  • WDM
  • back reflection
  • buried waveguide


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